The former House speaker saw his crowd sizes swell into the thousands, including an event at a U.S. flag-draped Sarasota airport hangar and another overflow event at a town square in Naples. He also enjoyed a burst of fundraising with a week to go before Florida's presidential primary. An official at a political-action committee backing his White House bid said they were buying $6 million in Florida ad time.

All day, Gingrich made brief mentions of Romney. Gingrich referred to his rival as the moderate in a race in which conservative credentials matter most. He linked Romney to Florida's former Republican governor-turned-independent, Charlie Crist, by talking about campaign staffers common to both men.

But he swung harder at Obama, saying he would offer the most striking choice against the incumbent in a November election.

Gingrich's remarks were partially timed to Tuesday night's State of the Union address. Gingrich said Obama should stop blaming his Republican predecessor for the country's economic woes.

"This is the fourth year of his presidency. He needs to get over it," Gingrich said. "A friend of mine says, 'He has shifted from 'Yes we can' to 'Why we couldn't.' "

Barely a half-year after his campaign all but imploded, Gingrich is reveling in a surge. He rebounded from disappointing showings in Iowa and New Hampshire to trounce Romney in South Carolina. Since then, he has shot to the front of many polls in Florida and nationally.

It's showing in his campaign finances, too. Gingrich officials said they raised more than $2 million since his win Saturday in South Carolina and expected hundreds of thousands more from finance events Tuesday.

A fundraising appeal sent out to supporters Tuesday underscored the newfound confidence.

Winning Our Future, a super PAC run by former Gingrich adviser Rick Tyler, said separately that it would use its newly purchased ad time to criticize Romney on health care. Romney approved a health law as governor of Massachusetts that some have described as a model for the controversial insurance mandate achieved by Obama. The PAC is financed largely by the family of a Las Vegas casino magnate.